Looking into modding my amp

[Kingofpain678]

Here is the stock schematic of my amp

http://bestnetworx.com/uploader/files/52/Peavey Windsor SCHEMATIC.pdf



Here are the mods in schematic form -

Pre mod



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Power section mod



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and finally a list of the mods to be done:
The easiest way to work on this amp is to label and remove all of the wires and work on the PCBs from the bottom (they're single sided boards). Use solder wick and a low wattage iron and the parts are easily removed. Note: The ribbon cable that connects the preamp and power amp PCBs does not have to be removed. Try to avoid damaging the parts that you remove. Some of them can be used for the mods.


****CAUTION***** There are no bleeder resistors on the power supply caps Drain them before proceeding.

Preamp
1.) Jumper C2
2.) Add 1nF cap from VR1 "w" to VR1 "h"
3.) Remove R13
4.) Change R4 to 10k
5.) Remove C5
6.) Jumper R14
7.) Replace R5 with 820 ohm
8.) Remove C28
9.) Remove C18
10.) remove R56
11.) Remove R70
12.) Jumper from V2-1 to V2-7
13.) Replace R21 with 100k
14.) Remove C41
15.) Jumper R65
16.) Remove C6
17.) Jumper from V2-8 to the R3 / R36 junction
18.) Remove R36
19.) Replace R3 with 33k
20.) Replace C24 with 470p
21.) Replace C13 with 22n

Power amp

1.) Replace R45 with 100k 1W
2.) Connect a 3.3n cap across R45
3.) Replace R41, R42, R43, and R44 with 1k 5w

Power supply
1.) Connect a 330k across C10 (bleeder)
2.) Connect a 330k across C12 (bleeder)

R59 (400 ohm 10w ) should be replaced with a choke.

So, this is supposed to JCM800-ize my amp. And, this amp is cheap enough that I could not only mod this one but also buy another one and keep it stock.

So, here are my issues... I have no idea where to buy the pieces I need to mod this amp, if someone could help me out with that, that would be great.
Next, I don't know what I'm doing BUT my buddy is an electrical engineer and agreed to help me out with this. I know basic soldering and all that and he knows the technical side so this would be a joint effort.

So, if anyone with any electronic smarts could point me in the direction to get these parts and/or let me know if they have any objections to the mods listed - please let me know

 

[PRHunt]

If you want to source your stuff with minimum fuss, then try online ordering with Digikey or Mouser. I didn't have a close look at the parts required, but if there's any tubes or "boutique" sort of stuff needed, then you might need a specialist audio supplier. Parts Connexion in Canada is an "audiophile" DIY supplier - you can source a variety of fancy caps, resistors, pots, tubes, wire etc. Hope that helps.

Paul

 

[drumslinger]

i don't see anything on the list that is boutique. Mouser or Digikey should have everything you need. As you know......You'll be working with High Voltage and caution should be taken. "****CAUTION***** There are no bleeder resistors on the power supply caps, Drain them before proceeding" is a good clue. I've been building tube amps for nearly 7 years and I still freak out when working with High Voltage which keeps me on my toes. I would start by changing out the 1k/5W resistors and then try out the amp. Do the mods in stages. You might end up liking what you hear after one or a few mods. Your ears will tell you. Have fun and be safe.

DS

 

[ranjam]

The mod looks silly to me, but then again I can't get a decent zoom and resolution to know with 100% certainty what the mod is calling for. But what I can tell is you are goosing a little gain in the pre in one spot, reducing it in another, running the tone stack as a Cathode-follower instead of Plate-loaded, and then trimming the gain down in the end. Makes no sense. And bumping the Screen Grid resistors down to 1K is just another thing to shun. I don't get it. It makes no sense. It's kinda like saying to take your '54 Mercury with a 256, bore out the pistons to 312, but still leave the compression ratio at 7.5:1 like it was still a 256. Not that a Peavey Windsor is a '54 Mercury, but hopefully I make more sense than this mod. I'd leave it alone. If you really don't like the tone, you can tweak it slightly, and goose the gain, but after that I'd look more into buying a different amp.

 

[Kingofpain678]

The mod looks silly to me, but then again I can't get a decent zoom and resolution to know with 100% certainty what the mod is calling for. But what I can tell is you are goosing a little gain in the pre in one spot, reducing it in another, running the tone stack as a Cathode-follower instead of Plate-loaded, and then trimming the gain down in the end. Makes no sense. And bumping the Screen Grid resistors down to 1K is just another thing to shun. I don't get it. It makes no sense. It's kinda like saying to take your '54 Mercury with a 256, bore out the pistons to 312, but still leave the compression ratio at 7.5:1 like it was still a 256. Not that a Peavey Windsor is a '54 Mercury, but hopefully I make more sense than this mod. I'd leave it alone. If you really don't like the tone, you can tweak it slightly, and goose the gain, but after that I'd look more into buying a different amp.

The tone stack is wacky and the gain stages are sorta wacky too... too much compression way too fast.

I've pretty much lost hope seeing as how the guy who was going to lead the way in this project has changed his mind.

 

[ranjam]

You want to reduce the gain cheaply? Try lower gain tubes. Try a 12AY7 for V1. I don't have a Windsor schematic, but check the bias. Try swapping out the phase inverter. There's 'cheap' mods you can do that aren't really mods, but they can sure make a difference.